In general, rimless spectacles fix lenses through lens fixing apparatuses respectively fixed to a bridge and temples of the spectacles at the state where a fixing rim surrounding each lens has been removed. While using the rimless spectacles, a shape of the lens can be freely fabricated to fit into the shape of a wearer's face. Also, since only lenses without having any rims surrounding the lenses are used and put on, the rimless spectacles are very light. Further, since a wearer's face is not so much hidden by the rimless spectacles, a demand on the rimless spectacles is increasing nowadays.
As shown in FIG. 1, in the case of a lens fixing apparatus 10 in such a conventional rimless spectacles, one end of a bending portion 5 to which one side of a temple of the rimless spectacles is hinge-coupled, is weld-combined with one of holders for fixing both ends of a lens 1, and one end of a bridge 9 is weld-combined with the other of holders. Likewise, one end of a bending portion of the other temple of the rimless spectacles and the other end of the bridge 9 are weld-combined with holders for fixing both ends of the other lens.
In this case, a combining hole 15 having a diameter D1 corresponding to that of a fixing bolt 17 is formed on each fixing frame 13 in the lens fixing apparatus 10. Likewise, a through-hole 3 having a diameter D2 corresponding to that of the fixing bolt 17 is formed on each side of the lens 1.
In this manner, the lends 1 is fixed to the fixing frame 13 by the fixing bolt 17 which pierces the through-hole 3 of the lens 1 and the combining hole 15 of the fixing frame 13 in turn and a nut 19 combined with the fixing bolt 17.
By the way, the pair of the above-described conventional rimless spectacles has required a procedure of establishing perforating positions of the through-holes 3 accurately and perforating the through-holes 3, so that a distance L2 between the center of the through-hole 3 and the side end of the lens 1 can be maintained in correspondence to a distance L1 between the center of the combining hole 15 of the fixing frame 13 and the inner side of a holder 11, in order to make the side surface of the lens 1 compressively contact the inner side of the holder 11 when the lens 1 is made fixed to the fixing frame 13, differently from a pair of common eyeglasses where an assembly of lenses can be done quickly by loosening fixing bolts combined with only a glasses frame and then fitting the lenses into the glasses frame, after the correction lenses have been processed to fit into the eyesight of a glasses wearer.
Thus, an eyeglasses expert should set a position to be perforated in order to perforate the through-hole 3 via the combining hole 15 using an auger, at the state where the lens 1 has been put in front of the lens fixing frame 13, and then drilled manually to thereby form the through-hole 3.
By the way, since the eyeglasses expert should perforate the through-hole 3 on the lens manually, it is very difficult to maintain the lengths of “L1” and “L2” to equal each other as shown in FIG. 1. If a distance between the center of the through-hole 3 and the side end of the lens is set larger than “L2,” the side end of the lens 1 does not compressively contact the inner side of the holder 11. As a result, it is not possible to fix the lens 1 to the fixing frame 13.
Also, in the case that a distance between the center of the through-hole 3 and the side end of the lens is set smaller than “L2,” the side end of the lens 1 does not completely closely contact the inner side of the holder 11, and a gap is formed between the side end of the lens 1 and the inner side of the holder. In this state, in the case that the fixing bolt 17 and the nut 19 are combined with the lens 1 and the fixing frame 13, a combining force F to be formed by the fixing bolt 17 and the nut 19 is generated by a combining force Fy only in the axial direction of the fixing bolt 17. Accordingly, the rear surface of the lens 1 is compressively fixed to the front surface of the fixing frame 13.
Thus, when a wearer is wearing the rimless spectacles, the lens 1 is twisted around the fixing bolt 17 in the case that a vibration and a shock is transferred to the rimless spectacles. If such a phenomenon is repeated, the fixing bolt 17 and the nut 19 are gradually loosened.
As a result, the wearer is apt to feel eye strain easily since his or her eye's focus does not match that of the lens due to the twisted lens 1, and his or her eyesight is deteriorated as well.
Meanwhile, as described above in the conventional case, the through-hole 3 of the lens 1 cannot but be perforated equally at a position where the side surface of the lens is compressively attached to the holder 11. Accordingly, a curvature, a degree and a thickness of the lens which are applied differently according to the degree of the eyesight of the wearer, have not been considered.
As a result, in the case that a lens is a thicker concave lens which becomes thicker as it goes to the outer wall of the lens, the fixing bolt 17 combined with the through-hole 3 of the lens obstructs a wearer's field of vision. In the case that a lens is a thinner convex lens which becomes thinner as it goes to the outer wall of the lens, portions which support the fixing bolt 17 are thin. Accordingly, since the thin portions of the lens do not bear up the combining force of the fixing bolt and the nut, the lens is broken.
Also, the glasses experts who assemble the rimless spectacles should concentrate on work for a long time in order to accurately work a small-sized through-hole 3 on the lens to fit into a position of the combining hole 15 as described above, quickly at the state where many customers stand by. Accordingly, a degree of fatigue from work increases and an assembly productivity decreases. If the through-hole 3 of the lens has not been accurately perforated at a set position, the lens 1 is not used and then is discarded.